The two driven members are especially suitable for connection to respective ones of the inner shaft and the outer tube of an assembled SCP (single cam phaser) camshaft. In such a camshaft, a first set of cam lobes is mounted for rotation with the outer shaft and a second set of cam lobes is freely rotatable relative to the outer tube but connected for rotation with the inner shaft by pins that pass with clearance through tangentially elongated slots in the outer tube. In this way, the invention enables the timing of both the inner shaft and outer tube of the camshaft to be changed relative to the crankshaft using only a single actuator and control system. This offers a high level of valve timing flexibility at a considerably reduced cost, when compared to an engine with two fully independent phasing systems.